Circuit breaker with piston gas flow and selective synchronous operation



June 25.1968 R. R. ctR'cLE ETAL. 3,

. CIRCUIT BREAKER WITH PISTON GAS FLOW AND SELECTIVE SYNCHRONOJS OPERATION Filed Feb. 26, 1955 2 Sheets-Sheet 1 FlG.l

FULLY OPEN-CIRCUIT POSITION WITNESSES INVENTORS L Robert R. Circle BBYTh mus O. Prunty ZXZZZaAeL/E M ATTORNEY am V25. 1968 R. Rcmcu; ETAL CIRCUIT BREAKER WITH'PISTON GAS FLOW AND Filed Feb. 26, 1965 SELECT IVE SYNCHRONOUS OPERATION 2 Sheets-Sheet 2 CONTINUED OPENING MOVEMENT United States Patent 015cc 3,39%,240 Patented June 25, 1968 CIRCUIT BREAKER WITH PISTON GAS FLOW AND SELECTIVE SYN CHR'ON OUS OPERATION Robert R. Circle, Woodbridge, Va., and Thomas 0.

Prunty, New Orleans, La., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania 'Filed Feb. 26, 1965, Ser. No. 435,557 Claims. (Cl. 200-148) ABSTRACT OF THE DISCLOSURE A puffer-type gas-flow circuit interrupter has main contacts in electrical parallel with light synchronouslyoperated contacts, and a single piston device to supply gas flow to either set of contacts dependent upon the current magnitude being interrupted. The synchronouslyoperated contacts have a first chance at interruption, while the main orifice is blocked by the moving main contact. If synchronous interruption does not occur because of light overload currents, then the main orifice is unplugged by continued opening movement of the main movable contact, and conventional puifer flow by the piston device effects interruption of such light overload currents within the main orifice in the usual manner.

This invention relates, generally, to circuit breakers and, more particularly, to circuit breakers of the type having synchronously operated contacts which are opened just prior to a current zero of an alternating current wave.

One of the problems encountered when building a synchronous circuit breaker is that of providing contact members heavy enough to carry large amounts of current yet light enough to permit them to be opened in the short time available for synchronous operation, particularly at 60 cycle frequency.

An object of the invention is to provide a circuit breaker having relatively heavy main contacts which are opened non-synchronously and relatively light secondary contacts which are opened synchronously.

Another object of the invention is to provide for interrupting high fault currents synchronously at current zero by first opening the main contacts thus diverting current flow through the secondary contacts in response to a trip signal and then opening the secondary contacts just prior to a current zero.

A further object of the invention is to interrupt low fault currents by opening only the main contacts nonsynchronously.

Still another object of the invention is to utilize one puffer mechanism for supplying compressed gas to extinguish an are at either the synchronous or non-synchronous contact zone.

A still further object of the invention is to provide for directing all puffer gas flow to the zone in which interruption is to be effected, thereby conserving puffer energy.

Another object of the invention is to actuate the puffer piston and the main moving contact by means of the same operating mechanism.

A further object of the invention is to actuate the secondary moving contact by means of gas pressure developed by the puifer and controlled by a valve operated by a synchronous operator.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with one embodiment of the invention, the main or non-synchronous contacts and the secondary or synchronous contacts of a circuit breaker are connected in parallel-circuit relation when the breaker is closed. The main contacts carry most of the current since they are of a heavier construction and provide a shorter path having a low voltage drop through the breaker. When the breaker begins to open, all of the current is shunted through the secondary contacts which are opened just prior to a current zero by gas pressure developed by a puffer and controlled by a valve operated by a synchronous operator. The same puffer supplies gas to extinguish the are drawn either at the synchronous contacts which interrupt high fault currents or at the nonsynchronous contacts which interrupt currents too low to operate the synchronous operator. The putfer and the main moving contact are actuated by the same operating mechanism.

For a better understanding of the nature and objects of the invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a longitudinal sectional view taken through a circuit breaker incorporating principles of the present invention, the contact structure being shown in the fully open-circuit position; and,

FIGS. 2-4 are views, similar to that of FIGURE 1, but illustrating the same breaker in various stages during the opening operation.

Referring to the drawings the circuit breaker structure shown therein comprises a housing 10, terminal bushings 11 and 12 mounted on the housing 10, main contact means 13, secondary contact means 14, puffer means 15, a synchronous operator 16 for operating a valve 17, and a mechanical linkage 18 interconnecting the putter means 15 and a movable main contact member 19. The housing or tank 10 contains an interrupting gas, preferably sulfur hexafluoride (SF gas, at a relatively low pressure, on the order of 2 to 3 atmospheres. Other interrupting gases, even air, may be utilized if desired.

The main contact means 13 includes a relatively stationary contact finger assembly 21, an orifice member 22 having an arcing ring 23 disposed in a generally cylindrical throat 24 of the orifice member, the generally cylindrical movable contact member 19 which passes through the throat 24 to engage the base of a generally cup-shaped member 25 movably disposed in the finger assembly 21, a contact finger assembly 26 slidably engaging the movable contact member 19, and an insulating member 27 having one end attached to the movable member 19 and the other end connected to the mechanical linkage 18. The finger assembly 26 is mounted in an insulating body member 28 and the assembly 26 is electrically connected to a portion 29 of the terminal bushing 12. The cup-shaped member 25 is biased outwardly in the finger assembly 21 by a compression spring 31. The finger assembly 21 is electrically connected to a conductor 32 which, in turn, is connected to a portion 33 of the terminal bushing 11. The main contact members are of a relatively heavy construction. Thus, when the movable contact member 19 is closed to engage the member 25 and then the fingers 21 a current path have a relatively low resistance therethrough, and a low voltage drop is provided through the circuit breaker from the terminal bushing 11 to the terminal bushing 12. The bushings 11 and 12 may be connected to suitable power conductors.

The secondary contact means 14 includes a relatively stationary contact finger assembly 34 and a generally cylindrical movable contact member 35 which normally closes the entrance at one end of a hollow cylindrical metal flow direction and stationary contact member 36, which is electrically connected to the arcing ring 23 by a conductor 37. The movable member 35 is biased outwardly in the contact finger assembly 34 by a compression spring 38. A piston 39 is attached to the member 35 and slidably disposed in a cylinder 41 to disengage the member 35 from the member 36 when actuated by the gas pressure as will be described more fully hereinafter.

The finger assembly 34 is electrically connected to the conductor 32. Thus, when the contact member 35 engages the member 36, as shown in FIG. 2, the secondary contact means 14 and the primary contact means 13 are connected in parallel-circuit relation through a circuit, which extends from the main contact finger assembly 21 through the conductor 32, the secondary contact finger assembly 34, the secondary movable contact member 35, the stationary member 36, the conductor 37 and the arcing ring 23, which engages the main movable contact member 19 when this member is in the closed position, as shown in FIG. 2. However, the secondary contact members are of a relatively light construction, and the current path through these members is longer than the path through the main contact members. Therefore, the path through the secondary members has a higher resistance than the path through the main contact members, which carry most of the current when the circuit breaker is fully closed, as shown in FIG. 2.

The puffer means comprises a piston 42 slidably disposed in a cylindrical portion 43 of the main body member 28 and a piston rod 44 which may be driven by a suitable operating mechanism (not shown). The operating mechanism may be of a type well known in the art. The piston 42 is shown in the fully opened position of the circuit breaker in FIG. 1. When the circuit breaker is fully closed, as shown in FIG. 2, the piston 42 is at the other end of the cylinder 43.

As shown, the mechanical linkage 18 comprises a lever 45 pivotally mounted on a fixed support 46, a link or link 47, which connect one end of the lever 45 to one end of the insulating member 27, and links 48 which connect the other end of the lever 45 to a projection 49 on the piston rod 44. The lever 45 may comprise two members which straddle the rod 44. Likewise, the links 47 and 48 may comprise two spaced members. Thus, the puffer and the main moving contact member 19 are so interconnected that when the puffer is driven in one direction to compress the interrupting gas, the main contact member 19 is driven in the opposite direction to be disengaged first from the contact finger assembly 21 as shown in FIG. 3 and later from the arcing ring 23 as the member 19 moves towards its fully opened position, as shown in FIG. 4. The linkage mechanism 18 may be so constructed that the puffer piston 42 travels a greater distance and at a higher linear speed than the movable contact member 19, thereby providing a high gas pressure.

The synchronous operator 16 may be of the type fully described in a copending application Ser. No. 97,656, filed Mar. 22, 1961, now US. Patent 3,215,866, issued Nov. 2, 1965 to Fritz Kesselring and Lutz Seguin. As described in the aforesaid application, the synchronous operator comprises a saturating magnetic core 51 having a plurality of air gaps therein and a moving coil or armature 52 rotatably mounted in a main air gap 53. The moving coil 52 comprises a winding closed upon itself and may consist, for example, of a rectangular copper or aluminum frame. The conductor 37 passes through a central opening 54 in the magnetic core 51. Thus, the core is energized by the current flowing through the conductor 37 which is the current to be interrupted by the secondary contact means 14 of the circuit breaker.

As described in the aforesaid copending application, the core 51 unsaturates when the current decreases below a predetermined amount and the rapid rate of change in the flux in the core 51, which takes place as the current in the conductor 37 approaches zero, induces a secondary current in the armature coil 52, which reacts with the flux across the air gap 53 to produce a torque which rotates the armature coil 52. This torque is utilized to operate the valve 17 which is mounted on a shaft 55 of the armature 52. The valve 17 may be of the type fully described in a copending application Ser. No. 98,522, filed Mar. 27, 1961 now US. Patent 3,215,804, issued Nov. 2, 1965 to Fritz Kesselring. Valves of other types may be utilized.

When the breaker begins to open in response to a trip signal, as shown in FIG. 3, and the main or non-synchronous contact 19 is separated from the contact member 25 by the operating mechanism, all of the current is shunted through the conductor 32 to the secondary contact fingers 34, the secondary or synchronously operated contact member 35, the metallic flow director and the stationary contact member 36, the conductor 37, the arcing ring 23, the main contact member 19 and the finger assembly 26 to the terminal bushing 12. Thus, the synchronous operator 16 is energized by the current to be interrupter by the circuit breaker, as shown in FIG. 3 and the orifice opening 24 is blocked to prevent gas flow therethrough, as shown in FIG. 3.

The operator 16 may be so constructed that it will open the valve 17 only at relatively large fault currents, as shown in FIG. 3. Furthermore, the synchronous operator may be constructed to open the valve 17 a short time, for example about two milliseconds, before a current zero. When the valve 17 is opened, the gas compressed by the puifer 15 flows through a passageway 56 to actuate the piston 39, thereby disengaging the contact member 35 from the stationary secondary contact member 36 just prior to current zero where the small instantaneous current are is extinguished by the flow of gas from the putter through the arc region and out through the metallic flow director 36. Should the synchronous interrupter fail to interrupt the current, the valve 17 will reclose immediately after current zero by a reversal of the torque provided by the synchronous operator 16, and the moving synchronous contact 35 will close under the influence of the biasing spring 38, to open again at the next current zero in the manner hereinbefore described with reference to FIG. 3. During this time, as mentioned the throat 24 of the orifice 22 is closed by the contact member 19, thereby directing all of the gas flow through the passageway 56, as shown in FIG. 3.

If the current level is too low for the synchronous operator 16 to operate, the valve 17 will remain closed as shown in FIG. 4. Continued motion of the main moving contact 19 will draw an are 68 between the arcing ring 23 and the main moving contact 19, as shown in FIG. 4. Simultaneously, with the drawing of this low current are 68, the throat 24 of the orifice 22, in which the arcing ring 23 is located, is uncovered allowing flow of the compressed gas from the puffer 15 through a passageway 57 across the are 68 within the orifice 24, thereby effecting interruption by conventional puffer action, as shown in FIG. 4.

When the throat 24 is closed by the main contact member 19, as shown in FIG. 3, all of the puffer gas is directed through the valve 17 and the passageway 56 to actuate the piston 39 and interrupt the arc 65 drawn between the synchronous contacts during the initial portion of the opening operation, as shown in FIG. 3. When the valve 17 is closed, all of the putter gas is directed through the passageway 57 to interrupt the are 68 drawn between the arcing ring 23 and the non-synchronous main contact 19 during the later portion of the opening operation, as shown in FIG. 4. Thus, all of the puffer gas fiow is directed to the particular zone in which interruption is to be efiiected, thereby conserving puffer energy.

One puffer mechanism supplies compressed gas for synchronous as well as non-synchronous interruption. The same operating mechanism drives the putter mechanism and the main moving contact 19, which are interconnected by the mechanical linkage 18.

The non-synchronous main contacts are of a relatively heavy construction, thereby permitting them to carry high load currents with a low voltage drop and to interrupt low fault currents below the level at which the synchronous operator 16 functions, as shown in FIG. 4. The synchronous or secondary contacts are of a relatively light construction, thereby permitting them'to be opened by the synchronous operating mechanism 16 just prior to a current zero to efiect interruption at current zero, as shown in FIG. 3.

From the foregoing description it is apparent that the invention provides a circuit breaker of the puffer type that will interrupt low fault currents and perform loadbreak switching. When the breaker begins to open, all of the current is shunted through the secondary or synchronous contacts, as shown in FIG. 3, thereby giving these contacts the first chance to interrupt high fault currents. The breaker is of a relatively simple construction and may be economically manufactured and installed.

Since numerous changes may be made in the abovedescribed construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all subject matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illutsrative and not in a limiting sense.

We claim as our invention:

1. In a synchronous-type circuit breaker, in combination, relatively movable main non-synchronous contacts and relatively movable secondary synchronously-actuated contacts connected in electrically parallel ciruit relation whean the breaker is closed, a puffer for compressing an interrupting gas to obtain a source of pressurized gas, mechanical means interconnecting the puffer and the main movable non-synchronous contact to open the main non-synchronous contacts when the puffer is driven in a direction to compress the gas during the opening operation, gas-pressure actuated means for opening the secondary synchronously-actuated contacts, valve means for controlling the flow of said pressurized gas from said puffer to the pressure actuated means, and a synchronous operator responsive to the main current flow through the circuit breaker for operating said valve means.

2. In a synchronous-type circuit breaker, in combination, relatively movable main non-synchronous contacts and relatively movable secondary synchronously-actuated contacts connected in electrically parallel circuit relation when the breaker is closed, a putter for compressing an interrupting gas to obtain a source of pressurized gas, mechanical means interconnecting the pufi'er and the main movable non-synchronous contact to open the main non-synchronous contacts when the puffer is driven in a direction to compress the gas during the opening operation, gas-pressure actuated means for opening the secondary synchronously-actuated contacts, valve means for controlling the flow of said pressurized gas from said puffer to the pressure actuated means, and a synchronous Operator responsive to the main current flow through the circuit breaker and energized by the current flowing through the secondary contacts for operating the valve means.

3. In a circuit breaker, in combination, relatively heavy main contacts for establishing a low resistance'path for current through the breaker when closed, normally closed relatively light secondary contacts, a putter for compressing an interrupting gas, mechanical means actuated by the puffer to open the main contacts and shunt the current through the secondary contacts when the putter is driven in a direction to compress the gas during the opening operation, gas-pressure actuated means for opening the secondary contacts, valve means for controlling the flow of gas from the putter to the pressure-actuated means, and a synchronous operator energized by the current flowing through the secondary contacts for operating said valve means.

4. In a circuit breaker, in combination, relatively heavy main contacts for establishing a low resistance path for current through the breaker when closed, normally closed relatively light secondary contacts, a putter for compressing an interrupting gas, mechanical means actuated by the puffer to open the main contacts and shunt the current through the secondary contacts when the puffer is driven in a direction to compress the gas during the opening operation, gas-pressure actuated means for opening the secondary contacts, valve means for controlling the iiow of gas from the putter to the pressure actuated means, a synchronous operator energized by the current flowing through the secondary contacts for operating said valve means, and said gas being directed to extinguish the are drawn at the secondary contacts.

5. In a circuit breaker, in combination relatively heavy main contacts for establishing a low resistance path for current through the breaker when closed, normally closed relatively light secondary contacts, a puller for compressing an interrupting gas, mechanical means actuated by the puffer to open the main contacts and shunt the current through the secondary contacts when the putter is driven in a direction to compress the gas during the opening operation, gas-pressure actuated means for opening the secondary contacts, valve means for controlling the flow of gas from the putter to the pressure-actuated means, a synchronous operator energized by the current flowing through the secondary contacts for operating said valve means, and means for directing gas from the puifer to the main and the secondary contacts to extinguish arcs at said contacts.

6. A circuit interrupter comprising main contact means, secondary contact means, putter means for compressing an interrupting gas to obtain a source of pressurized gas, mechanical means interconnecting the puffer means and the main contact means to open the main contact means when the gas is being compressed by the puffer means during the opening operation, gas-pressure actuated means for opening the secondary contact means, valve means for controlling the flow of pressurized gas from the putter means to the pressure actua ed means, and a synchronous operator energized by the current flowing through the secondary contacts for operating said valve means.

7. A circuit interrupter comprising main contact means including a relatively stationary main coni'act member, an orifice member, a main contact member movable through the orifice member to engage the stationary contact member, an arcing member disposed in the orifice member, secondary contact means including a relatively stationary secondary contact member, a spring-biased movable secondary contact member normally engaging the stationary secondary contact member, piston means for disengaging the secondary contact members, pufler means for compressing an interrupting gas, mechanical means actuated by the pufier means to disengage the movable main contact member from the stationary main contact member during the opening operation, valve means for controlling the flow of compressed gas from the puffer means to the piston means, and a synchronous operator energized by the current flowing through the secondary contacts for operating said valve means.

8. A circuit interrupter comprising main contact means including a relatively stationary pin contact member, an orifice member, a main movable contact member movable through the orifice member to engage the stationary contact member, an arcing member disposed in the orifice member, secondary contact means including a relatively stationary secondary contact member, a spring-biased movable secondary contact member normally engaging the stationary secondary contact member, piston means for disengaging the secondary contact members, puffer means for compressing an interrupting gas, mechanical means actuated by the puffer means to disengage the movable main contact member from the stationary main contact member during the opening operation, valve means for controlling the flow of compressed gas from the puffer means to the piston means, a synchronous operator energized by the current flowing through the secondary contacts for operating said valve means, and means for directing the compressed gas from the puffer means to either the secondary contact means or the main contact means to extinguish arcs drawn at said contact means.

9. A circuit interrupter comprising main contact means including a relatively stationary main contact member, an orifice member having a generally cylindrical throat, a generally cylindrical main movable contact member movable through said throat to engage the stationary contact member, an arcing ring disposed in the throat to engage the movable contact member, secondary contact means including a hollow cylindrical stationary contact member, a spring-biased movable secondary contact member normally closing one end of the hollow cylindrical member, piston means for disengaging the spring-biased member from the hollow cylindrical member, conducting means electrically connecting the stationary main contact member and the spring-biased movable secondary contact member, additional conducting means electrically connecting the hollow cylindrical member and the arcing ring, puffer means for compressing an interrupting gas, mechanical means interconnecting the putter means and the movable main contact member to disengage the movable main con tact member from the stationary main contact member when the putter means is driven in a direction to compress the gas during the opening operation, valve means for controlling the flow of compressed gas from the puller means to the piston means, and a synchronous operator energized by the current flowing through the secondary contacts for operating the valve means.

10. A circuit interrupter comprising main contact means including a relatively stationary main contact member, an orifice member having a generally cylindrical throat, a generally cylindrical movable main contact member movable through said throat to engage the stationary contact member, an arcing rlng disposed in the throat to engage the movable contact member; secondary contact means including a hollow cylindrical stationary contact memher, a spring-biased movable secondary contact member normally closing one end of the hollow cylindrical member, piston means for disengaging the spring-biased member from the hollow cylindrical member, conducting means electrically connecting the stationary main contact member and the spring-biased movable secondary contact member, additional conducting means electrically connecting the hollow cylindrical member and the arcing ring, pufier means for compressing an interrupting gas, mechanical means interconnecting the putter means and the movable main contact member to disengage the movable main contact member from the stationary main contact member when the puffer means is driven in a direction to compress the gas during the opening operation, valve means for controlling the flow of compressed gas from the puffer means to the piston means, a synchronous operator energized by the current flowing through the secondary contacts for operating the valve means, and means for directing the compressed gas from the puffer means to either the secondary contact means or the main contact means to extinguish arcs drawn between the stationary secondary contact member and the spring-biased movable secondary contact member or between the arcing ring and the movable main contact member.

References Cited UNITED STATES PATENTS Re. 21,125 6/1939 Ruppel 200-148 2,051,659 8/1936 Uebermuth 200148 3,215,866 11/1965 Kesselring et al 200148 ROBERT S, MACON, Primary Examiner. 

